1. Field of the Invention
The present invention relates generally to material deposition processes, and more particularly, but not exclusively, to micromechanical system structures and manufacturing methods.
2. Description of the Background Art
A micro electromechanical system (MEMS) typically includes micromechanical structures that may be actuated using electrical signals. An example of a MEMS device is the Grating Light Valve™ (GLV) device available from Silicon Light Machines, Inc. of Sunnyvale, Calif. GLV-type devices are described in the following disclosures, which are incorporated herein by reference in their entirety: U.S. Pat. No. 5,311,360 to Bloom et al.; U.S. Pat. No. 5,841,579 to Bloom et al.; and U.S. Pat. No. 5,661,592 to Bornstein et al.
Generally speaking, a GLV-type device is a light modulator. It may be used in various applications including video, printing, and optical switching, for example. A GLV-type device includes an array of moveable structures referred to as “ribbons”. A ribbon typically includes a metallic layer formed over a resilient, suspended structure. Under the ribbon is a bottom electrode that works in conjunction with the metallic layer, which serves as a top electrode. An air gap separates the bottom electrode from the metallic layer. Applying a voltage difference between the ribbon and the bottom electrode generates an electrostatic field that pulls the ribbon towards the bottom electrode. Light that impinges on the reflective metallic layer may thus be modulated by reflection or diffraction by controlling the applied voltage.
The response of a GLV-type device to a control signal, such as an applied voltage, is also referred to as its “driving characteristic”. As can be appreciated from the foregoing, the better a device's driving characteristic, the better it can modulate light. Thus, it is desirable to have a GLV-type device that has a relatively stable driving characteristic. Furthermore, the selling price of a light modulator takes into account the cost of the manufacturing equipment employed to fabricate the light modulator. Therefore, a technique that would allow for the use of cost-effective manufacturing equipment in the fabrication of a light modulator or other devices would be desirable.